For some time now the favicons in tabs seem to be interchangeable, e.g. the avast! favicon on the avast! forum tab turns up on my local bank tab, or the Softpedia favicon turns up on the DonationCoder forum tab.

Oh yes, favicons sometimes get messy :-/
Usually it's "fixed" when force-reloading a page (right-click on Reload button), and although only 1 page is reloaded, the favicons of all other tabs also seem to get updated, funny. Sometimes I could reproduce a mess when there are tabs with page load error for some reason, or something like that, if offline sometimes the messy icon just jumped 1 tab forward, the whole round